What is SIBO?

SIBO = Small Intestinal Bacterial Overgrowth

What is SIBO?

siboSmall intestinal bacterial overgrowth (SIBO) occurs when the small intestine becomes colonized by large numbers of bacterial flora that are normally restricted to the colon and terminal ileum (end of small intestine). These bacteria feed on and ferment the small intestinal content and produce gasses (methane, hydrogen, hydrogen sulphide) that then result in the below symptoms.

Simple explanation: Bacteria which normally belong in your large intestine move in reverse to the small intestine where they don't belong. These bacteria then eat the partially digested food in the small intestine. Upon eating the food they release gas, which can be compared to a balloon in the small intestine that gets larger and larger with the more gas that is produced. Because the gas can not easily escape (as it can in the large intestine) it causes the symptoms of abdominal pain and bloating.

Gastrointestinal Symptoms:

  • Bloating
  • Nausea
  • Cramping and pain
  • Excess gas
  • Altered bowels including diarrhea (linked to hydrogen overgrowth) and constipation (linked to methane overgrowth)
  • Malabsorption and malnutrition (deficiencies of vitamins and iron)
  • Weight loss

Manifestations outside GI:

  • Flu like symptoms
  • Fatigue
  • Anxiety
  • Depression
  • Muscle pain
  • Impaired cognition
  • Anemia
  • Rosacea

Bodies Defence Mechanisms:

  • Gastric acid secretion
  • Intestinal motility (particularly phase 3 of the migrating motor complex)
  • Intact ileocecal valve (exists between the small and large intestine)
  • Immunoglobulins within intestinal secretions
  • Anti-bacterial properties of pancreatic and biliary secretion

Associated Conditions:

  • Achlorhydria (low stomach acid often secondary to proton pump inhibitors)
  • Pancreatic insufficiency
  • Immune deficiency syndromes
  • Small intestinal obstruction
  • Diverticula
  • Fistulae
  • Surgical blind loop
  • Previous ileo-cecal resections
  • Motility disorders

Increased Prevalence of SIBO in Following Conditions:

  • Irritable Bowel Syndrome (IBS)
  • Celiac disease
  • Crohn’s disease
  • Short bowel obstruction
  • Non-alcoholic steatohepatitis
  • Autonomic neuropathy in diabetes mellitus
  • Post radiation enteropathy
  • Fibromyalgia
  • Scleroderma
  • Amyloidosis

Other Conditions Associated with or Complicated by SIBO:

  • Obesity
  • Lympoproliferative diseases (lymphoma, chronic lymphocytic leukaemia)
  • Benign lymphoid hyperplasia of the ileum
  • Metabolic bone disease
  • Acromegaly
  • Hypothyreosis
  • Alcoholism
  • Rosacea
  • Parkinsons disease
  • The presence of SIBO rises with age (about 50% in persons 75 years of age or older)
  • Medications that slow gut motility: narcotics, anticholingergics and anti-diarrheals